1,364 research outputs found
A First-Order Dynamical Transition in the displacement distribution of a Driven Run-and-Tumble Particle
We study the probability distribution of the total displacement
of an -step run and tumble particle on a line, in presence of a
constant nonzero drive . While the central limit theorem predicts a standard
Gaussian form for near its peak, we show that for large positive and
negative , the distribution exhibits anomalous large deviation forms. For
large positive , the associated rate function is nonanalytic at a critical
value of the scaled distance from the peak where its first derivative is
discontinuous. This signals a first-order dynamical phase transition from a
homogeneous `fluid' phase to a `condensed' phase that is dominated by a single
large run. A similar first-order transition occurs for negative large
fluctuations as well. Numerical simulations are in excellent agreement with our
analytical predictions.Comment: 35 pages, 5 figures. An algebraic error in Appendix B of the previous
version of the manuscript has been corrected. A new argument for the location
of the transition is reported in Appendix B.
Some comments on global-local analyses
The main theme concerns methods that may be classified as global (approximate) and local (exact). Some specific applications of these methods are found in: fracture and fatigue analysis of structures with 3-D surface flaws; large-deformation, post-buckling analysis of large space trusses and space frames, and their control; and stresses around holes in composite laminates
Survival probability of an immobile target surrounded by mobile traps
We study analytically, in one dimension, the survival probability
up to time of an immobile target surrounded by mutually noninteracting
traps each performing a continuous-time random walk (CTRW) in continuous space.
We consider a general CTRW with symmetric and continuous (but otherwise
arbitrary) jump length distribution and arbitrary waiting time
distribution . The traps are initially distributed uniformly in
space with density . We prove an exact relation, valid for all time ,
between and the expected maximum of the trap process up to
time , for rather general stochastic motion of each trap.
When represents a general CTRW with arbitrary and
, we are able to compute exactly the first two leading terms in the
asymptotic behavior of for large . This allows us subsequently to
compute the precise asymptotic behavior, , for large , with exact expressions for the stretching exponent
and the constants and for arbitrary CTRW. By choosing
appropriate and , we recover the previously known results
for diffusive and subdiffusive traps. However, our result is more general and
includes, in particular, the superdiffusive traps as well as totally anomalous
traps
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